As many of you are aware the Museum
has been hosting the Great LA Air Raid for some time now. The
event started out with less than 50 people and one searchlight
and is now bringing in around 700 people, a tank, vehicles and
aircraft flyovers and as many as five searchlights. 3 years ago
Mr. Tom Horsfall attended one of the air raid events. Tom is a
radio enthusiast, researcher, restorer and operator and has many
electronic/ mechanical museum restorations under his belt.
Together with other Museum volunteers Tom operated the Museum’s
1942 GE searchlight (its official name is the 352nd Coast
Artillery Anti-Aircraft Searchlight Battalion Memorial
Searchlight) and was part of our demonstration team. Tom
commented to the others that it would be a lot better to
demonstrate the light with its Distant Electric Control station
or DEC instead of operating it with the manual control arm.
Unfortunately the Museum’s light had been modified for
commercial use and all of the necessary equipment had been
stripped off with all connecting wires cut and the system was
basically destroyed. The DEC system allows the light to be controlled from a distant
location. The DEC is a stand alone station connected to the
light through a cable. The DEC allows the operator to look
through a set of binoculars to acquire the target and then the
operator can track the target without being blinded by the light
itself. While lights, generators and DECs are still obtainable,
it is very difficult to find fully operational sets.

Tom, who lives in Richmond
California 400+ miles away from San Pedro, approached the Museum
with the idea of restoring the light. He came up with the plan
to make monthly 3 day visits to the museum and felt that within
one year he could have the system up and running. Previously the
museum had been told that it would be virtually impossible to
restore the light to its 1942 configuration. Beginning in January 2009 Tom began making his visits. His first
visit was scheduled to conduct an inventory of missing parts and
manuals. He steadily acquired the manuals and carefully studied
the schematics and learned how the light worked. The next few
visits were spent cleaning the light and searching for missing
parts. His searches led him from former commercial operator’s
junk yards, to military museums and to remote desert boneyards.
Throughout the state he travelled acquiring parts and pieces.
Wiring looms were especially difficult to obtain because almost
all of the parts lights had been stored outside and the rubber
insulation had seriously decayed. In other cases the interior
wires were tested and had no conductivity. Furthermore, most
commercial operators discarded or destroyed the DEC related
equipment so not every visit produced results. One of the first
major problems came after locating the parts. The system requires two amplydines and a dynamotor to provide
the necessary AC and DC power to run the system. In addition
there are multiple internal sylsens (servos) that communicate with the
other electronics to effectively operate the system. While he
did find many of the parts he discovered disasters with them.
The amplydine interiors were damaged and had to be rebuilt. The
Dynamotor had been the home for a very large desert ant
community and was almost totally worthless and the Selsyn
housings were made of a magnesium alloy that had corroded and
expanded with the intrusion of moisture resulting in the
destruction of delicate interior wiring. So, he had the missing
parts, all of which needed complete overhaul and in some cases
were beyond resurrection. Tom, through a myriad of contacts
located individuals to assist him with the rebuilding of the
amplydines and dynamotor and paid for the restoration on behalf
of the museum. He went back to the commercial
operators again buying parts personally for the project. He then
made yet another trip to a very remote desert boneyard with a
one trip collective 1000 miles travel to gain parts. The trip
was held up by the selsyns. It seemed that nearly every example
from as many as five different lights were damaged beyond
repair. Still, through steadfast dedication he was able to find
operational units for the operation of both the azimuth and the
elevation of the light. About six months into the project he had
all of the parts needed but now the real work started; the
wiring of the system. The looms were originally part of an
assembly line production. In many cases looms and leads were
installed and then other looms for other control systems were
installed over the DEC leads or sometimes tied with them. More
significantly the commercial operators had simply cut the multi
conductor cables with hack saws at the junction boxes in some
cases ripped them out. The trick was to figure out the right
cables for the right terminal blocks inside the various junction
boxes. Once inside the project was made more complicated by the
discovery that some terminal blocks had their numbering system
located at the top of each terminal connection point while
others had them below the terminal connectors. So after
carefully reweaving the looms into place every wire had to be
tested once again before work could proceed. Another set of
parts that proved difficult to find were the small brushes that
ride on the collector rings. There were a few brushes corroded
in place on the light that had to be removed and then new
brushes with the very delicate springs and wires had to be
located.

Craig Michelson of the American
Museum of Military History located in Rosemead said that he had
some derelict lights in his storage yard and that he would be
willing to donate them to the project. These small brushes were
carefully installed and we were ready to begin testing. This
series of testing lasted until the fall of 2009. With more
progress with each passing month Tom brought more and more of
the light back into operation.The first test came with the Azimuth control from the DEC. Tom
brought a small portable power supply that simulated the power
from the generator for the DEC system. Tom commented “You know
if this works first time out it will be a miracle”. The system
did not work. First a fuze in the main terminal box failed and
then an after market fuze was somehow tied into the main switch
box and it had to be removed. Next test, azimuth began to move
with DEC control. Staff marveled at Tom’s work but we soon
noticed that the light was moving opposite the controller as tom
directed it left the light moved right. Unfortunately, this test
was on the last day of Tom’s monthly visit so we were in
suspense for a month. When Tom return he examined the terminal
connections in the selsyn and found that here was a case of the
terminal number being on the opposite side of other terminal
numbers. So a switch of connection and we hade Azimuth control
for the first time. Next came elevation. We doubled checked
wiring and prepared for operation. We soon learned first hand,
although we knew from stories that commercial operators hated
the DECs because they can hurt you. If someone moves the light
while the DEC gears are engaged and then puts power to the DEC
the light will correct itself to the position determined by the
DEC and in a hurry! In our case the light was out about 180
degrees and it made the turn in a couple if seconds. It awesome
to see the light work on its own but was also a bit scary. Tom
showed us that if you inspect the instruments called “zero
readers” on the DEC one can adjust them to the light’s positions
and then switch power on the DEC and there will be no movement.
But woe bit it to those that forget.. The next problem
encountered was the movement of the light was not quite as
responsive as we thought it should be. This was determined to be
a faulty switch mechanism that Tom discovered during his trouble
shooting. We soon had a replacement switch and it seemed to fix
the issue. Still there was a stalling of the light in both
elevation and azimuth as it rotated. Tom soon traced this
problem to dirty and scarred collector rings in the base of the
light. Under careful supervision of Tom the rings were cleaned
and testing continued. The light was running smoothly on power from the power supply,
it remained to see what would happen when power came from the
generator itself and testing proceeded. The first run brought a
couple of blown fuzes but these failures were diagnosed by Tom
and quickly fixed by replacing them and cleaning the contacts.
All of the contacts of this light had been moisture damaged at
some point and cleaning them all was paramount. Soon, operation
of the DEC was accomplished with the arc burning and we all had
a great sense of elation. Tom had done the near impossible task
as described by other volunteers. The light was finished and
prepped just in time to be used in the 2010 Great Los Angeles
Air Raid event held in February 2010. The event was a great
success due in large part to the efforts of Tom Horsfall, Our
hat is off to you Tom!Tom is considering additional searchlight restoration projects
and would like to help the museum find a Sperry 1941 DEC unit or
any related parts. He would also like very much to find a sound
locator that was used with the lights so if you or anyone that
you know has searchlight related parts please have them contact
the Museum at (310) 548-2631.

The restoration of the
museums 352nd Coast Artillery Anti-Aircraft
Searchlight Battalion Memorial Searchlight has been
an ongoing project of the Fort MacArthur Museum for
several years now. To learn more about the history
behind this project, please visit our
restoration projects pages.